Off-highway industrial vehicles typically utilize dry or wet service brake and park brake assemblies. The service brakes are applied by applying hydraulic pressure to a slave cylinder. The dry brake slave cylinder applies pressure to friction brake shoes or discs which apply stopping torque to the wheel brake drums. In the case of a dry brake assembly, the slave cylinder is the wheel cylinder. For a wet brake axle, the slave cylinder is the brake piston. The piston applies pressure to an assembly of alternating friction discs and separator plates. The friction discs rotate with the wheel, axle shaft, or differential depending on the brake location. The separator plates are grounded to the drive axle housing.
The park brake assembly is most often actuated using park brake cables connected to various mechanical devices within the brake assembly or drive axle assembly. These park brakes are often actuated by a mechanical park brake lever assembly by the operator. The park brake cables often increase truck assembly complexity and cost.
In some cases, the park brake is actuated by a spring applied brake that functions in combination with or independently of the service brake. Typically, these spring applied park brakes are actuated separately from the service brake and require an additional park brake piston and the brake actuation system is increased in complexity. This park brake design requires two sets of working fluid brake lines; one for the service brake and one for the park brake. This increases vehicle assembly complexity and cost.
Another type of park brake system commonly used with off-highway industrial vehicles is a driveline brake. These brake assemblies usually comprise of friction discs and separator plates or a brake rotor and caliper assembly. These driveline park brake assemblies are typically located in series to the driveline.
The present invention addresses these and other problems.